1. Field of the Invention
The invention relates to a power control device and power control method that control electric power supplied from an external power supply to a vehicle.
2. Description of the Related Art
An electromotive vehicle, such as an electric vehicle and a hybrid electric vehicle, is in practical use. The electromotive vehicle is propelled by a motor that is driven by electric power stored in an electrical storage device. In addition, in recent years, development of a so-called plug-in vehicle has been proceeding. The plug-in vehicle includes a system that charges an electrical storage device with power supplied from an external power supply called, a charging station, or the like.
In connection with charging control over such a plug-in vehicle, for example, Japanese Patent Application Publication No. 6-245325 (JP-A-6-245325) describes a technique for simplifying charging operation. An electric vehicle described in JP-A-6-245325 includes a battery, a charging line for charging the battery, and a communication device that is connected to the charging line. On the other hand, an external power supply that supplies electric power to the electric vehicle includes a charging line, and a communication device that is connected to the charging line. When a connector of the electric vehicle is connected to a connector of the external power supply, the communication device of the electric vehicle transmits charging information, such as the type or voltage of the battery, to the communication device of the external power supply via the charging lines. The communication device of the external power supply charges the battery of the electric vehicle automatically in an optimal condition in accordance with the charging information from the electric vehicle. By so doing, charging operation for charging the battery of the electric vehicle may be simplified.
As described above, JP-A-6-245325 describes that communication is carried out between the electric vehicle and the external power supply and then control for charging the electric vehicle is executed at the side of the external power supply on the basis of the communication information. However, JP-A-6-245325 does not describe specific details of the communication information and a method of generating the communication information.
Particularly, the range of information that is transmittable by a signal transmitted from the external power supply to the electromotive vehicle (for example, the range of allowable current value of the external power supply, which is transmittable by a pilot signal) is limited to a value that falls within a predetermined range because of the specifications of the signal or the physical requirements of the external power supply. Therefore, there is a problem that a power range that allows control for charging the electromotive vehicle is limited. JP-A-6-245325 describes nothing about the above problem or measures therefor.